In wireless telecommunication, a User Equipment (UE) has to supply significant power to its radio frequency transceiver, fast analogue-to-digital-converters, wideband signal processing units, etc. While data rates of Long Term Evolution (LTE) systems exceed those of the Universal Mobile Telecommunications System (UMTS) by a factor of up to fifty, wireless device batteries still provide approximately the same capacity, so substantial improvements in power usage are necessary to operate at such high data rates and wide bandwidths. LTE power safe protocols include Discontinuous Reception (DRX) and Discontinuous Transmission (DTX), as defined in 3GPP TS 36.321. The protocols of both UMTS and LTE provide a set of functionalities allowing the UE to perform micro sleep events also in a Radio Resource Control (RRC) connected mode. For example, LTE allows an implementation to not constantly monitor the Physical Downlink Control Channel (PDCCH) every Transmission Time Interval (TTI). A DRX-DTX cycle (also referred to as a DRX cycle or duty cycle) includes an active state followed by an inactive period, which allows the UE to safe battery resources by turning off its transceiver for a certain time period in a DRX Sleep Mode.
In a connection configured for DRX between the UE and a base station, the UE and the base station have a common understanding of the DRX cycles as to a mandatory active time, cycle duration, and synchronization. Beyond the mandatory active time, the active state is maintained by the UE as long as data transfer is ongoing, leaving less time available for the DRX Sleep Mode.
Conventional implementations of the LIE power safe protocol aim at entering the DRX Sleep Mode of the UE as fast and as often as possible to maximize savings of power consumption. However, switching between the active state and the DRX Sleep Mode requires some time for controlled enabling and disabling of involved hardware units, system clocks, etc. For example, when uplink data for transmission arrives just after a transition to the DRX Sleep Mode, it takes time to bring the involved hardware units back to the active state, which results in a delayed transmission of the uplink data.